【主线待合】增加tail命令

lua/lua.c

@@ -485,8 +485,8 @@ static int l_cat(lua_State *L)
 
 static int l_tail(lua_State *L)
 {
-    const char *path = luaL_optstring(L, 1, "C:rd.log");
+	long n = luaL_optinteger(L, 1, 15);
-    long n = luaL_optinteger(L, 2, 15);
+    const char *path = luaL_optstring(L, 2, "C:rd.log");
 
     long start_off = 0;         /* 实际输出的起始偏移 */
     long lines = 0;             /* 文件总行数 */
@@ -667,7 +667,7 @@ static int luaopen_default(lua_State *L)
     lua_register_help(L, "name", l_name, "Show build time");
 	lua_register_help(L, "echo", l_echo, "eg: echo(\"Hello\", \"C:a.txt\")");
     lua_register_help(L, "cat", l_cat, "eg: cat(\"C:a.txt\")");
-    lua_register_help(L, "tail", l_tail, "eg: tail(\"C:rd.log\")  tail(\"C:rd.log\", 30)");
+    lua_register_help(L, "tail", l_tail, "eg: tail(30)  tail(30, \"C:rd.log\")");
     lua_register_help(L, "mv", l_mv, "eg: mv(\"C:a.txt\", \"C:b.txt\")");
     lua_register_help(L, "rm", l_rm, "eg: rm(\"C:a.txt\")");
     lua_register_help(L, "ls", l_ls, "eg: ls()");